[R] Reorder in decreasing order

[Duncan Murdoch]

On 12-07-22 5:33 PM, arun wrote:
> Hi Duncan,
>
> That was my original suggestioin.  His reply suggests that it is not that he wanted.

I didn't see your reply.  Maybe you sent it privately?  In any case, I 
think it is up to Sverre to give an example of what he wants, since your 
suggestion, Weidong's and mine all appear to do what he asked for.

Duncan Murdoch

> "
>
> Not quite. It still orders the values in an increasing order, you've
> just changed the values here. I'm using reorder() to prepare for
> plotting the values, so I can't change the values."
>
>
> bymean2<-with(InsectSprays,reorder(spray,count,function(x) -mean(x)))
>>    bymean2
>>    [1] A A A A A A A A A A A A B B B B B B B B B B B B C C C C C C C C C C C C D D
>> [39] D D D D D D D D D D E E E E E E E E E E E E F F F F F F F F F F F F
>> attr(,"scores")
>>            A          B          C          D          E          F
>> -14.500000 -15.333333  -2.083333  -4.916667  -3.500000 -16.666667
>> ####################
>> Levels: F B A D E C
>> #######################
> A.K.
>
>
>
> ----- Original Message -----
> From: Duncan Murdoch <murdoch.duncan at gmail.com>
> To: Sverre Stausland <johnsen at fas.harvard.edu>
> Cc: r-help at r-project.org
> Sent: Sunday, July 22, 2012 4:56 PM
> Subject: Re: [R] Reorder in decreasing order
>
> On 12-07-22 12:27 PM, Sverre Stausland wrote:
>> reorder() is probably the best way to order the levels in a vector
>> without manually specifying the order. But reorder() orders by default
>> in an increasing order: "The levels are ordered such that the values
>> returned by ‘FUN’ are in increasing order."
>>
>> Is there a way to do what reorder() does, but order the levels
>> according to a _decreasing_ order of the values?
>
> Yes, as Weidong suggested:
>
>> x <- rnorm(20)
>> y <- factor(sample(letters[1:3], 20, replace=TRUE))
>> reorder(y, x, mean)
> [1] a a c c c b b a b a c c b b a a a a c a
> attr(,"scores")
>           a          b          c
> -0.2012975  0.6117830  0.2180352
> Levels: a c b
>>
>> reorder(y, x, function(x) -mean(x))
> [1] a a c c c b b a b a c c b b a a a a c a
> attr(,"scores")
>           a          b          c
> 0.2012975 -0.6117830 -0.2180352
> Levels: b c a
>
> Duncan Murdoch
>
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